It is probably a small glitch in the program, but I dont see anything seriously harmed.
in the first case, where you said everything is grayed, just enter company code and plant hit enter and all other fields become accesible
In the second case all fields are accessible, but company code and plant have a flag for mandatory entry.
Finally you have the same result.
when you start VEFU, then you get first the overview screen, which has only 2 fields open for maintenance: company code and plant. And the cursor is automatically in the company code field as it is the first field in the screen which is open.
To get your second case you actually have to move the cursor away from the editable field, which is a step more. Based on this, I would even say that you may have found a feature instead of a bug.